Automatic water valve for rock drills



Dec. 27, 1955 G, H, FUEHRER 2,728,328

AUTOMATIC WATER VALVE FOR ROCK DRILLs Filed may 18, 1955 A wl) 54 1 i 4747 5 A, 42 i5 Z9 4?/ 97 ,477@ j, 2@ 49 576. 4;

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United States Patent AUTOMATIC WATER VALVE FR ROCK DRILLS George H.Fuehrer, Downey, Calif., assigner to Thor Power Tool Company, LosAngeles, Calif., a corporation of California Application May 1g, 1953,Serial No. 355,679

Claims. (Cl. 121-10) This invention relates to automatic valves, andparticularly to an air-operated valve for controlling the flow of waterto the cutting head of a rock drill in accordance with the position ofthe drill throttle valve.

In rock drill structures of the type in which cleaning water is fedthrough the drill to the drill bit, it is conventional to provide awater tube plug in the backhead of the drill and adjacent the outer endof a removable water tube. Such a construction makes possible thereplacement of the water tube upon mere removal of the water tube plug,so that the drill need not be lifted out of the mine when the water tubeis broken. In my co-pending patent application Serial No. 325,005, tiledDecember 9, 1952, for an Automatic Water vValve for Rock Drills, I havedescribed and claimed an improved automatic water valve which is shapedas a water tube plug and may be substituted for it, and which isremovable when it is desired to replace a broken water tube.

The present invention constitutes an improvement over the structureillustrated in my co-pending application, and is particularly directedto the solution of the following problems which may arise in the use ofthe described automatic valve, particularly where adequate maintenanceand lubrication operations are not carried out. The first problem isthat of sticking of the valve components after the initial lubricationhas been lost. It is highly important in mining operations, where dirtand water are frequently present at the drill, that the water valve bedesigned to prevent sticking even in the absence of adequate lubricationor in the presence of foreign matter such as particles of dirt or dust.A second important problem is that of preventing the opening of thewater valve, and consequent ow of water to the drill bit, when thethrottle valve is in the off position and no drilling operation is inprogress. It is inherent in a rock drill, particularly after aconsiderable amount of use and consequent wear on the drill components,that a certain amount of air pressure seeps from the inlet air line andinto the drill. This air pressure may, after a substantial length oftime, build up to a point where the automatic water valve is shifted toopen position and the flow of water commenced at an undesired time. Athird important problem is that of providing an automatic water valveand associated throttle valve which, in accordance with requirements ofa particular customer, may or may not be adapted to effect water flow tothe drill bit during the collaring or starting hole portion of thedrilling operation.

These and other objects and advantages of the invention will be morefully set forth in the following specifica- 'tion and claims consideredin connection with the attached drawing to which they relate- In thedrawing:

Figure l is a vertical sectional View of the backhead of a rock drill,the section being taken longitudinally of the drill and illustrating thecomponents of the automatic valve of the invention;

Figure 2 is a view corresponding to Figure 1 but illustrating the watervalve in closed position;

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Figure 3 is a fragmentary view of the throttle valve portion of Figures1 and 2, and showing the throttle valve in a third position at which thewater valve is vented through the machine and permitted to asume aclosed positiomand Figure 4 illustrates a throttle valve of a secondembodiment of the invention adapted to elect flow of water during thecollaring operation.

Referring to the drawing, the illustrated structure may be seen tocomprise a backhead 10 provided at the outer end of a conventional rockdrill, not shown, a throttle valve 11 mounted in backhead 10 and adaptedto control the flow of air to the motor components of the drill, and anautomatic water valve 12 associated with throttle valve 11 incontrolling the flow of cleaning water to the drill bit. In addition tothese elements specifically illustrated, the drill components at thebackhead further comprise a handle and a suitable lubricating chamber,both not shown.

The backhead 10 is formed with a generally cylindrical chamber 13adapted to receive the unshown motor valve components of the drillingapparatus, and with a communicating chamber or passage 14 extendingaxially of chamber 13 to the end of the drill for mounting of theautomatic water valve 12 and associated elements. The upper portion ofthe backhead is provided with a relatively large transverse bore 15adapted to receive the air throttle valve 11, and which communicatesthrough a passage 16 with the chamber 13. Extending parallel to bore 15is a second and smaller transverse bore 17. This bore is connected atone end to a suitable water hose, not shown, and communiates at itsother end with the passage or chamber 14.

The air throttle valve 11 comprises a tubular body 19 which is mountedin bore 15 and adapted with a handle 2i) for manual rotation todifferent controlling positions. The tubular body 19 connects to an airsupply hose, not shown, and serves as an air conduit between the hoseand passage 16 leading to the drill motor. For this purpose a relativelylarge full speed port 21 is provided in valve body 19 and disposed toregister with the full diameter of passage 16 when the valve is in thefull speed position shown in Figure l. A second and smaller port 22,known as the collaring port, is arcuately offset from the full speedport 21 and registers with passage 16 when the valve is in the collaringposition shown in Figure 2. In the operation of the valve, the drill bitis first positioned at the desired location on the rock to be bored, andthe throttle valve 11 is rotated to the Figure 2 position. A relativelysmall volume of air then flows through the small collaring port 22 andthe passage 16 to the drill motor, so that the drill is operated at lowspeed and a starting or collaring hole formed in the absence ofexcessive drill movement. After the drill bit is rmly located in thecollaring hole, the throttle valve 11 is rotated to the Figure 1position at which a large volume of air flows through the relativelylarge full speed port 21 and passage 16 to effect full speed drilloperation. The precise location of valve 11 at the various illustratedpositions is insured through use of suitable detent means, not shown.

The automatic water valve 12 comprises a generally cylindrical casing 24threaded into the passage 14, and a piston or plunger 25 adapted to beaireactuated longitudinally of casing 24 to control the flow of waterfrom inlet passage 17 to the drill bit. The water circuit thuscontrolled is through a water tube 26 which extends longitudinally ofthe full length of the drill and into passage 14, there being a flangeat the end of tube 26 for seating on the bottom of a suitable washer cup27. Cup 27, in turn, is provided with an external flange for pressingconnection with an annular packing member 28 which is nested in acylinder 29 forming part of the internal epesses.

components of the drill itself. The flange of washer cup 27 is pressedagainst packing 28 by the inner end of water valve casing 24, the latterbeing suitably recessed at 31 to lit over the body of the washer cup.The inner end or rim of the casing 24 is suitably notched or ported, asshown at 32, to provide water passages between water bore 17 and recess31. A water chamber is thus provided in passage 14, and is sealed by thepacking 2S and by an O-ring 33 mounted between the unthreaded inner endof casing 24 and the cooperating passage wall. This Water chamber is tobe distinguished from an air chamber formed in passage 14 and sealedboth by the O-ring 33 and by a gasket 34 mounted between a shoulderportion of casing 24 and a cooperating seat on the backhead.

The plunger 2S of water valve 12 is formed with a small diameter inneror stem portion 36, a medium diameter stop portion 37 outwardly adjacentstem 36, and a relatively large diameter flange or piston disc portion38 outwardly of stop portion 37. The stem portion 36 is freely slidablewithin a corresponding axial bore in casing 24 and is provided with aconical inner end 39 for sealing engagement with a rubber washer 41, thelatter being mounted in washer' cup 27 adjacent the hanged endV of thewater tube. The stop portion 3'7 of plunger 25 is mounted in a casingchamber of substantially larger diameter, so that an annulus 42 isprovided between the plunger and its casing for passage of air as willbe described. The piston disc 33 is mounted in a correspondingcylindrical piston chamber 43 formed axially of casing 24 at its outerend.

Air passage means for connecting throttle valve 11 and piston chamber 43are provided in the form of a longitudinal passage 44 formed in casing24 and communicating both with piston chamber 43 and annulus 42, and acommunicating radial passage 46 extending from the inner end of passage44 to the air chamber portion of passage 14. The air chamber portionadjacent casing passage 46 takes the form of an annular groove between ashoulder of the backhead and the inner thread member of the valve casing24. This groove communicates through an upwardly extending passage 47with the air bore 1S.

As shown in Figure l, the location of collaring port 22 is such that itregisters with passage 47 when the valve is in the full speed position,so that air is then admitted from air bore and through collaring port22, passages 47, 46, and 44 to the inner end of piston chamber 43. Thepiston disc 3% is thus air pressed outwardly to shift the plunger to itsopen position permitting the flow of water through water tube 26. Whenthe piston disc 38 is at the outer position, its outer edge is seatedagainst a stop disc 49 which is maintained at the outer end of chamber43 by a snap ring 51. The stop disc 49 is provided with an axial port 52to effect venting of the air behind piston disc 38 when it shifts toopen the valve.

For the majority of applications of the automatic water valve structure,it is not desired that water ow to the drill bit during the collaringoperation. Accordingly, an arcuate venting groove 54 is provided on theexternal surface of throttle valve body 19 and disposed to connectpassage 47 and a venting port 56 when the valve is rotated to thecollaring position illustrated in Figure 2. At this time the supply ofpressure air to the piston disc 38 is blocked, and the air at the innerend of piston chamber 43 is vented through passages 44, 46 and 47, andthrough arcuate groove 54, to the port 56 which leads to the atmosphere.A helical compression spring 57, seated between disc 49 and the bottomof a spring chamber at the outer end of plunger 25, is then effective toshift the plunger to its water blocking position at which the stopportion 37 of the plunger is seated on a shoulder 58 formed in casing 24at the outer end of the bore for stem 36. The conical end 39 of theplunger then being spring pressed against sealing washer 41, the ow ofwater from water bore 17 and through the water chamber to water tube 26is effectively blocked.

Referring to Figure 3, the spring return movement of the plunger 25 isalso el'ected when the throttle valve 11 is rotated to off position, atwhich neither the collaring port 22 nor the full speed port 21 registerswith passage 16 leading to the drill motor. Venting in this instance iseffected through the drill body, with the arcuate groove 54 connectingthe passage 4'" and passage 16.

According to the invention, the described air actuation of plunger 25between closed and open positions is effected even in the absence ofadequate lubrication and after a substantial number of opening andclosing operations under adverse conditions. To accomplish this result,the diameter of piston disc 33 is made substantially smaller than thatof piston chamber 43, and no seal is provided on the periphery of thepiston disc. Instead, an O-ring S9, formed of rubber or other suitableelastomer, is tixedly mounted in an annular groove 61 at the outer endof piston chamber 43. The side walls of groove 61 are defined by ashoulder in casing 24 and by the stop disc 49, while the bottom wall ofgroove 61 is defined by an axially extending cylindrical casing surface.It will be noted that the depth of groove 61 is only about half thediameter of the O-ring 59, which is cylindrical in section when itsundeformed state. To provide for the sealing engagement between O-ring59 and the plunger 2S, the outer edge of piston disc 3S is beveled toform a frusto-conical surface 62 adapted to engage the inner portion ofO-ring 59, and a surface 63 which extends radially from the inner edgeof surface 62. rl`he surface 63 is spaced, relative to the outer end ofplunger 2S, so that it forms a continuation of the inner wall of O-ringgroove 6i when the valve is in its open position as shown in Figure l,the plunger end then being seated on stop disc 49 as previously stated.

The above construction is to be distinguished from previousconstructions in which an O-ring is provided on the piston disc 3S formovement with it. Such an O-ring, because of its relatively large size,has a distinct tendency to stick in the presence or particles of foreignmatter and in the absence of proper lubrication. Al though an O-ring 64is provided on stem portion 36 of plunger 25, to prevent seepage ofwater into the air components of the water valve, this O-ring is ofextremely small cross-section and diameter and does not impede thevalve-shifting operations even in the absence of lubrication.

When the drill is in its off position (Figure 3), any

seepage of air from the throttle valve 11 and into the drill and thepiston disc chamber 43 will not be effective to shift the water valve toits open position since, as above indicated, a clearance is providedbetween the piston disc and cooperating chamber wall. The seepage airthus merely leaks through the clearance annulus and out vent 52, withoutshifting the piston disc. Preferably, this clearance is on the order of.001 to .002 inch difference between the diameters of piston disc 38 andpiston chamber 43. Upon rotation of throttle valve 11 to the full speedposition (Figure l), the plunger 25 shifts to open position due to thelarge volume of air suddenly acting against the piston disc. Thefrusto-conical surface 62 then seats on O-ring 59 and provides a tightsealing engagement preventing any further air seepage through theclearance annulus. The plunger will then be effectively maintained inopen position as desired, and without wastage of air. When the throttlevalve is again rotated to the o position of Figure 3, the intentionalsupply of pressure air to the water valve is blocked and a venting pathcreated through passage 44 and into the drill. The spring 57 then shiftsplunger 25 in the return direction to again close the water valve.

As previously indicated, for some applications of the drilling apparatusit is desirable that water be applied to the drill bit even during thecollaring operation. The present apparatus may be adapted to accomplishthis result by merely removing a plug 66 from the end of a passage 67 inbackhead 10, and substituting the valve body 68 illustrated in Figure 4for the body 19 shown in Figures l through 3. The passage 67interconnects the drill chamber 13 with the annular groove in passage14, which communicates through passages 46 and 44 with the pistonchamber 43. The tubular body 68 of throttle valve 11 is constructed thesame as body 19 except that the arcuate venting groove 54 is notprovided.

Referring to Figure 2, it will be noted that when the throttle valve 11is in its collaring positionan air path is created from air bore 15 andthrough collaring port 22, passage 16, and chamber 13 to passage 67, theplug 66 being removed. From passage 67 the air flows through the annulargroove to radial passage 46 and longitudinal passage 44 leading to theinner end of piston chamber 43. The resulting pressure in chamber 43effects shifting of plunger 25 to open the water valve and permit the owof water. It will be noted that this pressure actuation of the plunger25 during the collaring operation would not be possible if the valvebody 19 of Figures l through 3 were employed since the pressure frompassage 67 would vent through port 56 to the atmosphere instead ofshifting the plunger. When the embodiment of Figure 4 is employed, andthe valve is in the full speed position shown in Figure 4, parallel airpaths are formed to the chamber 43. One path is through the passages 47,46 and 44, and another path is through passage 16, chamber 13, passage67, and passages 46 and 44. When the throttle valve of Figure 4 is inthe oi position, venting is through passage 67 to the body of the drill.

To summarize the operation of the drilling apparatus, let it rst beassumed that the plug 66 is positioned, as indicated in Figures lthrough 3, to block passage 67, and that the tubular valve body 19 isemployed. With the throttle valve 11 in the off position (Figure 3) thedrill bit is engaged with the rock face and at the desired location, thewater valve 12 then being closed since the pressure connection topassage 47 is blocked. The throttle valve 11 is then rotated to thecollaring position shown in Figure 2, and air is admitted throughcollaring port 22 and passage 16 to the drill motor to effect its lowspeed operation until a collar hole is bored. At this time the plunger25 of water valve 12 is in its left or inner position, with the conicalend 39 of the plunger serving to block the end of water tube 26 andprevent iiow of water to the drill bit. The collar hole having beenbored, the throttle valve 11 is rotated to the full speed position ofFigure l, and air is admitted through port 21 and passage 16 for fullspeed operation of the drill motor. At this time, the collaring port 22registers with passage 47 to admit air through passages 46 and 44 to theinner end of piston chamber 43, the air pressure pressing the plunger 25to its outer or open position against the bias of spring 57. Water thenflows from water bore 17, through the notched or ported end 32 of valvecasing 24, and around the end of washer cup 27 to the water tube 26 andthe drill bit. At the completion of the drilling operation, the throttlevalve is rotated to the position of Figure 3, operating to block thepressure connection to passage 47 and complete a venting path frompiston chamber 43 through passages 44, 46 and 47 and venting groove 54to backhead passage 16 and the drill body. The spring 57 then returnsplunger 25 to its huid-blocking position. If it is desired to switchfrom full speed to collaring position instead of to the off position ofFigure 3, the operation of the water valve is the same except that theventing path is through groove 54 and out port 56 to the atmosphere.

In applications where it is desired to supply water to the drill bitduring collaring, the plug 66 is removed and the valve body 68 of Figure4 is substituted for that previously described. The operation of thedrill is then the same except that parallel paths are created to pistonchamber 43 when the throttle valve 11 is in the full speed position ofFigure l, the second path being through the chamber 13 and passage 67 topassages 46 and 44 leading to the piston chamber. When the throttlevalve is in the collaring position, the plunger 25 is air actuated toits open position since a pressure path is then created throughcollaring port 22, passage 16, chamber 13, passage 67, and passages 46and 44 to the inner end of piston chamber 43. When the valve is rotatedto the oit position of Figure 3, the spring 57 becomes operative toreturn the plunger 25 to water-blocking position, the venting path thenbeing through passage 67.

Because of the substantial clearances provided, and the use of thestationary O-ring 59 instead of an O-ring on the movable piston disc 38,the plunger 25 is free for either air or spring actuation even in theabsence of a lubricating substance. For the same reasons the returnspring 57 may be made relatively weak, so that only a minimum oppositionis created to the shifting of the plunger to open position by the airpressure from the throttle valve.

While the particular apparatus herein shown and described in detail isfully capable of attaining the objects and providing the advantageshereinbefore stated, it is to be understood that it is merelyillustrative of the presently preferred embodiments of the invention andthat no limitations are intended to the details of construction ordesign herein shown other than as defined in the appended claims.

I claim:

1. In an air-operated automatic water valve for a rock drill, a valvecasing defining a cylindrical piston chamber, a piston disc reciprocablymounted in said piston chamber and adapted to control the ow of water tothe cutting bit of said rock drill, said piston disc having clearancebetween its peripheral surface and the interior piston chamber-definingsurface of said valve casing to provide substantially trictionlesssliding of said piston disc in said piston chamber and permittingseepage of air through sail clearance space, passage means to conductpressurized air from a source of supply to one side of said piston discto shift the same to one extreme position, and a sealing element liXedlymounted in said casing on the other side of said piston disc thereoffrom said air supply, said sealing element being disposed to sealinglyengage both said interior casing surface and said piston disc to preventseepage of air through said clearance space when said piston disc is insaid one extreme position.

2. An automatic water valve for use in the backhead of an air-operateddrill controlled by a throttle valve, said drill having a water tubeadapted to conduct water to the drill bit from a chamber formed in thebackhead adjacent the end of said water tube and conventionallycontaining a water tube; which comprises a valve casing mounted in saidchamber in alignment with said water tube, a plunger mounted in saidcasing and slidable between outer and inner positions, said plungerbeing formed with a stem portion adapted when said plunger is in one ofsaid positions to block the flow ot water to said water tube and with apiston portion disposed in a piston chamber in said casing forsubstantially frictionless sliding movement therein, passage meansformed in said casing to conduct air pressure to one end of said pistonchamber for' shifting said plunger in one direction between said outerand inner positions, vent means for venting the opposite side of saidpiston to the atmosphere, means to return said plunger in an oppositedirection to its initial position after release of said air pressure,and a resilient sealing member ixedly mounted in said casing on thevented side of said piston, said sealing member being disposed to besealingly engaged by said piston portion when the same is in theposition assumed immediately after said air pressure shifting thereof.

3. The invention as claimed in claim 2, wherein a seal-free clearance isprovided between the periphery of said piston portion and thecorresponding wall of said piston chamber, the size of said clearancebeing suliicient to permit seepage of air around said piston portionprior to its engagement with said sealing member.

4. The invention as claimed in claim 2, wherein said clearance is on theorder of .001 to .002k inch difference in the diameter of said pistonportion and piston chamber.

5. The invention as claimed in claim 2, wherein said return means is acompression spring seated between said plunger and a stop surface at theouter end of said piston chamber.

6. The invention as claimed in claim 2, wherein said sealing member isan O-ring, and said piston portion is formed with a truste-conical endsurface adapted to be inserted through said O-ring for sealingengagement with its interior surface.

7. The invention as claimed in claim- 2, wherein said O-ring is seatedin an annular groove one side wall of which is formed by a stop disc atthe outer end of said piston chamber, the depth of said groove beingapproximately half the cross-sectional diameter of said O-ring.

8. A combination water valve and throttle valve mechanism for use in thebackhead of an air-operated rock drill, said rock drill having a watertube adapted to conduct water to the drill bit from a chamber formed inthe backhead adjacent the end of said water tube and conventionallycontaining a water tube; which comprises a valve casing inserted in saidchamber in alignment with said water tube, a tlanged valve elementmounted in said casing and movable between an open position and a closedposition blocking the flow of water through said water tube, theclearance between the flange of said valve element and cooperating wallof said casing being sufficient to permit seepage of air therebetweenwhen said valve element is in closed position, resilient sealing meansmounted at the outer end of said casing opposite the open position ofsaid flanged valve element for sealing engagement with said valveelement when the latter is in open position, a hollow throttle valvecylinder connected to a pressurized air supply means and rotatable todifferent drill-controlling positions, an air passage in said backheadand said valve casing and extending from said throttle valve cylinder toone end of the chamber enclosing said anged valve element, a port insaid throttle valve cylinder disposed to register with said air passagewhen the throttle valve is in a iirst controlling position, and aventing groove in the outer surface of said throttle valve cylinder,said venting groove being disposed to communicate with said air passageand with' a vent to the atmosphere when said throttle valve is in asecond controlling position blocking the ilow of pressurized air to saidanged valve element.

9. The invention as claimed in claim 8, wherein said sealing meanscomprises an O-ring, and said ange of said valve element is formed witha frusto-conical surface adapted to be inserted into sealing engagementwith said O-ring when said valve element is shifted to open position.

l0. A combination water valve and throttle valve mechanism for use inthe backhead of an air-operated rock drill, said rock drill having awater tube adapted to conduct water to the drill bit from a chamberformed in the backhead adjacent the end of said water and conventionailycontaining a water tube; which comprises a valve casing inserted in saidchamber in alignment with the water tube, a cylindrical valve elementfreely movable in said casing between an outer open position and aninner closed position blocking the ilow of water through said watertube, resilient sealing means fixedly mounted in said casing positionedto engage and seal the slight clearance between said casing and theperiphery of said valve element when the latter is in its open position,a hollow throttle valve cylinder connected to a pressurized air supplymeans and rotatable to different drill-controlling positions, a firstair passage extending from said throttle valve cylinder to the drillmotor chamber of saidrock drill, a second air passage extending fromsaid drill motor chamber to adjacent said ange on said movable valveelement, and port means in said throttle valve cylinder disposed toregister with said irst air passage when said throttle valve is in anoperating position, whereby air pressure is conducted through said firstand second passages to shift said valve element to open position.

References Cited in the tile of this patent UNITED STATES PATENTS2,215,217 Gustafson Sept. 17, 1940

